The risk of a global trade war has increased over the past four days after Donald Trump threatened to slap hefty tariffs on imported steel and aluminium.

Here, we look at what it all means.

Trade wars, what are they good for?

We are on the losing side of almost all trade deals. Our friends and enemies have taken advantage of the U.S. for many years. Our Steel and Aluminum industries are dead. Sorry, it’s time for a change! MAKE AMERICA GREAT AGAIN!

The US has made clear that no countries will be exempted from the tariffs, raising acute fears for British exporters.

Britain’s steel industry exports £360 million worth of products into the US every year, almost 15% of the sector’s total exports.

Gareth Stace, the director of trade body UK Steel, said: “In short, these measures would cause serious damage to the prospects of many steel producers here.”

What can the British Government do about it?

Theresa May attends church

Theresa May’s Government is holding out hope for a trade deal with the US that will make up for the inevitable loss of trade that comes with leaving the EU’s single market and customs union.

With the UK quitting the most powerful trading bloc in the world – the EU – it cannot risk alienating those it seeks new trading relationships with, so options are limited.

But Mrs May has told Donald Trump of her “deep concern” at his plan.

A Downing Street spokeswoman said over the weekend: “The Prime Minister raised our deep concern at the president’s forthcoming announcement on steel and aluminium tariffs, noting that multilateral action was the only way to resolve the problem of global overcapacity in all parties’ interests.”

Jean-Claude Juncker, the European Commission president, has said that in retaliation the EU would raise tariffs on US goods such as Kentucky bourbon, Levi’s jeans and Harley-Davidsons.

Raising the stakes further still, Mr Trump said the US would then put an import tax on cars made in the EU.

The president said on Twitter: “If the EU wants to further increase their already massive tariffs and barriers on US companies doing business there, we will simply apply a Tax on their Cars which freely pour into the US. They make it impossible for our cars (and more) to sell there. Big trade imbalance!”